[PATCH v7 17/25] ACPI / APEI: Pass ghes and estatus separately to avoid a later copy

James Morse
2018-12-03T18:23:07Z

The NMI-like notifications scribble over ghes->estatus, before
copying it somewhere else. If this interrupts the ghes_probe() code
calling ghes_proc() on each struct ghes, the data is corrupted.

All the NMI-like notifications should use a queued estatus entry
from the beginning, instead of the ghes version, then copying it.
To do this, break up any use of "ghes->estatus" so that all
functions take the estatus as an argument.

This patch just moves these ghes->estatus dereferences into separate
arguments, no change in behaviour. struct ghes becomes unused in
ghes_clear_estatus() as it only wanted ghes->estatus, which we now
pass directly. This is removed.

Signed-off-by: James Morse <james.morse@arm.com>

---
Changes since v6:
* Changed subject
* Renamed ghes_estatus to src_estatus, which is a little clearer
* Removed struct ghes from ghes_clear_estatus() now that this becomes
unused in this patch.
* Mangled the commit message to be different
---
drivers/acpi/apei/ghes.c | 84 +++++++++++++++++++++-------------------
1 file changed, 45 insertions(+), 39 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index b5c31f65a1c0..b70f5fd962cc 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -277,8 +277,9 @@ static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len,
}
}

-static int ghes_read_estatus(struct ghes *ghes, u64 *buf_paddr, int fixmap_idx)
-
+static int ghes_read_estatus(struct ghes *ghes,
+ struct acpi_hest_generic_status *estatus,
+ u64 *buf_paddr, int fixmap_idx)
{
struct acpi_hest_generic *g = ghes->generic;
u32 len;
@@ -295,25 +296,25 @@ static int ghes_read_estatus(struct ghes *ghes, u64 *buf_paddr, int fixmap_idx)
if (!*buf_paddr)
return -ENOENT;

- ghes_copy_tofrom_phys(ghes->estatus, *buf_paddr,
- sizeof(*ghes->estatus), 1, fixmap_idx);
- if (!ghes->estatus->block_status) {
+ ghes_copy_tofrom_phys(estatus, *buf_paddr, sizeof(*estatus), 1,
+ fixmap_idx);
+ if (!estatus->block_status) {
*buf_paddr = 0;
return -ENOENT;
}

rc = -EIO;
- len = cper_estatus_len(ghes->estatus);
- if (len < sizeof(*ghes->estatus))
+ len = cper_estatus_len(estatus);
+ if (len < sizeof(*estatus))
goto err_read_block;
if (len > ghes->generic->error_block_length)
goto err_read_block;
- if (cper_estatus_check_header(ghes->estatus))
+ if (cper_estatus_check_header(estatus))
goto err_read_block;
- ghes_copy_tofrom_phys(ghes->estatus + 1,
- *buf_paddr + sizeof(*ghes->estatus),
- len - sizeof(*ghes->estatus), 1, fixmap_idx);
- if (cper_estatus_check(ghes->estatus))
+ ghes_copy_tofrom_phys(estatus + 1,
+ *buf_paddr + sizeof(*estatus),
+ len - sizeof(*estatus), 1, fixmap_idx);
+ if (cper_estatus_check(estatus))
goto err_read_block;
rc = 0;

@@ -325,12 +326,13 @@ static int ghes_read_estatus(struct ghes *ghes, u64 *buf_paddr, int fixmap_idx)
return rc;
}

-static void ghes_clear_estatus(struct ghes *ghes, u64 buf_paddr, int fixmap_idx)
+static void ghes_clear_estatus(struct acpi_hest_generic_status *estatus,
+ u64 buf_paddr, int fixmap_idx)
{
- ghes->estatus->block_status = 0;
+ estatus->block_status = 0;
if (buf_paddr)
- ghes_copy_tofrom_phys(ghes->estatus, buf_paddr,
- sizeof(ghes->estatus->block_status), 0,
+ ghes_copy_tofrom_phys(estatus, buf_paddr,
+ sizeof(estatus->block_status), 0,
fixmap_idx);
}

@@ -638,9 +640,10 @@ static int ghes_ack_error(struct acpi_hest_generic_v2 *gv2)
return apei_write(val, &gv2->read_ack_register);
}

-static void __ghes_panic(struct ghes *ghes)
+static void __ghes_panic(struct ghes *ghes,
+ struct acpi_hest_generic_status *estatus)
{
- __ghes_print_estatus(KERN_EMERG, ghes->generic, ghes->estatus);
+ __ghes_print_estatus(KERN_EMERG, ghes->generic, estatus);

/* reboot to log the error! */
if (!panic_timeout)
@@ -650,25 +653,25 @@ static void __ghes_panic(struct ghes *ghes)

static int ghes_proc(struct ghes *ghes)
{
+ struct acpi_hest_generic_status *estatus = ghes->estatus;
u64 buf_paddr;
int rc;

- rc = ghes_read_estatus(ghes, &buf_paddr, FIX_APEI_GHES_IRQ);
+ rc = ghes_read_estatus(ghes, estatus, &buf_paddr, FIX_APEI_GHES_IRQ);
if (rc)
goto out;

- if (ghes_severity(ghes->estatus->error_severity) >= GHES_SEV_PANIC) {
- __ghes_panic(ghes);
- }
+ if (ghes_severity(estatus->error_severity) >= GHES_SEV_PANIC)
+ __ghes_panic(ghes, estatus);

- if (!ghes_estatus_cached(ghes->estatus)) {
- if (ghes_print_estatus(NULL, ghes->generic, ghes->estatus))
- ghes_estatus_cache_add(ghes->generic, ghes->estatus);
+ if (!ghes_estatus_cached(estatus)) {
+ if (ghes_print_estatus(NULL, ghes->generic, estatus))
+ ghes_estatus_cache_add(ghes->generic, estatus);
}
- ghes_do_proc(ghes, ghes->estatus);
+ ghes_do_proc(ghes, estatus);

out:
- ghes_clear_estatus(ghes, buf_paddr, FIX_APEI_GHES_IRQ);
+ ghes_clear_estatus(estatus, buf_paddr, FIX_APEI_GHES_IRQ);

if (rc == -ENOENT)
return rc;
@@ -819,17 +822,20 @@ static void ghes_print_queued_estatus(void)
}

/* Save estatus for further processing in IRQ context */
-static void __process_error(struct ghes *ghes)
+static void __process_error(struct ghes *ghes,
+ struct acpi_hest_generic_status *src_estatus)
{
-#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
u32 len, node_len;
struct ghes_estatus_node *estatus_node;
struct acpi_hest_generic_status *estatus;

- if (ghes_estatus_cached(ghes->estatus))
+ if (!IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG))
return;

- len = cper_estatus_len(ghes->estatus);
+ if (ghes_estatus_cached(src_estatus))
+ return;
+
+ len = cper_estatus_len(src_estatus);
node_len = GHES_ESTATUS_NODE_LEN(len);

estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool, node_len);
@@ -839,29 +845,29 @@ static void __process_error(struct ghes *ghes)
estatus_node->ghes = ghes;
estatus_node->generic = ghes->generic;
estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
- memcpy(estatus, ghes->estatus, len);
+ memcpy(estatus, src_estatus, len);
llist_add(&estatus_node->llnode, &ghes_estatus_llist);
-#endif
}

static int _in_nmi_notify_one(struct ghes *ghes, int fixmap_idx)
{
+ struct acpi_hest_generic_status *estatus = ghes->estatus;
u64 buf_paddr;
int sev;

- if (ghes_read_estatus(ghes, &buf_paddr, fixmap_idx)) {
- ghes_clear_estatus(ghes, buf_paddr, fixmap_idx);
+ if (ghes_read_estatus(ghes, estatus, &buf_paddr, fixmap_idx)) {
+ ghes_clear_estatus(estatus, buf_paddr, fixmap_idx);
return -ENOENT;
}

- sev = ghes_severity(ghes->estatus->error_severity);
+ sev = ghes_severity(estatus->error_severity);
if (sev >= GHES_SEV_PANIC) {
ghes_print_queued_estatus();
- __ghes_panic(ghes);
+ __ghes_panic(ghes, estatus);
}

- __process_error(ghes);
- ghes_clear_estatus(ghes, buf_paddr, fixmap_idx);
+ __process_error(ghes, estatus);
+ ghes_clear_estatus(estatus, buf_paddr, fixmap_idx);

if (is_hest_type_generic_v2(ghes) && ghes_ack_error(ghes->generic_v2))
pr_warn_ratelimited(FW_WARN GHES_PFX
--
2.19.2